[Central precocious puberty in girls: prediction of the etiology]

Precocious puberty (PP) is defined in girls by the occurrence of pubertal development before the age of 8. This development raises 3 questions: 1) Is it abnormal puberty or variant of the normal? 2) If abnormal puberty, is it of central, hypothalamic-pituitary, or peripheral, ovarian or adrenal origin? 3) If central, is it idiopathic or due to a lesion, and is there indication to treat it? The PP in a girl with no previous medical history is usually of central and idiopathic origin. However, isolated central PP may reveal a CNS lesion, particularly an optic glioma with its risk of blindness. Two independent predictors of CNS lesion are the age at PP onset of less than 6 years old, and increased plasma estradiol concentration. The selection of the girls for neuroradiological imaging should be based on these two parameters. However, neuroradiological imaging remains necessary until the prospective confirmation of their predictive value.